Stuffer box crimping and method therefor

ABSTRACT

A STUFFER BOX CRIMPER AND METHOD FOR CRIMPING FILAMENTARY MATERIAL, PARTICULARLY YARNS OF CONTINUOUS SYNTHETIC ORGANIC FILAMENTS, WHEREIN THE YARN IS CRIMPED AND UNIFORMLY WITHDRAWN FROM THE CRIMPER WITH A MINIMUM OF TENSION VARIATION. YARN FED TO THE APPARATUS IS COMPACTED AGAINST DOCTOR BLADES WHICH FORM OPPOSING SIDEWALLS OF THE STUFFER CHAMBER AND FRONT AND BACK PLATES WHICH COMPLETE THE STUFFER CHAMBER. THE YARN PROCEEDS THROUGH THE CHAMBER PACKED AGAINST THE CONFINING DOCTOR BLADES. THE DOCTOR BLADES DIVERGE A PREDETERMINED FRICTION-REDUCING AMOUNT WHILE BACK PRESSURE PRODUCING MEANS IN THE FRONT AND/OR BACK PLATE CALLED STABILIZERS, CONVERGE ON THE CONFINED YARN IN THE CHAMBER IN A DIRECTION GENERALLY PARALLEL TO THE DOCTOR BLADES AND AT AN   ANGLE OF 45 TO 135 DEGREES THERETO, THEREBY CHANGING THE FRICTIONAL IMPEDIMENT ON THE YARN FROM THE DOCTOR BLADES TO THE STABILIZER. THE CO-ACTION OF THE DOCTOR BLADES AND THE STABILIZER RESULTS IN THE FREE RELEASE OF CRIMPED YARN FROM THE CHAMBER IN A SMOOTH MANNER, THEREBY REDUCING VARIATIONS IN THE YARN TO A LEVEL SUITABLE FOR THE PIECE DYEING OF PRODUCTS PRODUCED THEREFROM WITH A MINIMUM OF DYE VARIABILITY.

Sept. 20, 1971 c, BlNFORD ETAL 3,605,221

STUFFER BOX CRIMPING AND METHOD THEREFOR Filed Aug. 8, 1969 3 Sheets-Sheet 1 FIGZ FIG I INVENTOR JACK C. BINFORD FREDRICK A. ETHRIDGE JAMES R. TALBOT BY jgfJZZljfW. HARRIS? ATTOR Sept. 20, 1971 J. c. BINFORD ETA!- STUFFER BOX GRIMPING AND METHOD THEREFOR Filed Aug. 8. 1969 3 Sheets-Sheet 2 FIG3 INVENTOR JACK C. BINFORD FREDRICK A. ETHRIDGE JAMES R. TALBOT DERYK W. HARRIS A NEY Sept. 20, 1971 c, BINFQRD EIAL 3,605,221

STUFFER BOX CRIMPING AND METHOD THEREFOR Filed Aug. 8, 1969 3 Sheets-Sheet 5 FIG 4 FIG 5 ATTO EY United States Patent 3,605,221 STUFFER BOX CRlMPlNG AND METHOD THEREFOR Jack C. Binford, Fredrick A. Ethridge, and James R.

Talbot, Charlotte, N.C., and Deryk W. Harrison, Greenville, S.C., assignors to Fiber Industries, Inc.

Filed Aug. 8, 1969, Ser. No. 848,495 Int. Cl. D02g 1/12 US. Cl. 231.6 12 Claims ABSTRACT OF THE DISCLOSURE A stuffer box crimper and method for crimping filamentary material, particularly yarns of continuous synthetic organic filaments, wherein the yarn is crimped and uniformly withdrawn from the crimper with a minimum of tension variation. Yarn fed to the apparatus is compacted against doctor blades which form opposing sidewalls of the stuffer chamber and front and back plates which complete the stuifer chamber. The yarn proceeds through the chamber packed against the confining doctor blades. The doctor blades diverge a predetermined friction-reducing amount while back pressure producing means in the front and/or back plate called stabilizers, converge on the confined yarn in the chamber in a direction generally parallel to the doctor blades and at an angle of 45 to 135 degrees thereto, thereby changing the frictional impediment on the yarn from the doctor blades to the stabilizer. The co-action of the doctor blades and the stabilizer results in the free release of crimped yarn from the chamber in a smooth manner, theerby reducing variations in the yarn to a level suitable for the piece dyeing of products produced therefrom with a minimum of dye variability.

BACKGROUND Stuffer box crimping is Well known in the art. Many methods of this type and apparatuses have been suggested for producing crimps in filamentary materials. While many of these apparatuses and methods have been suitable for certain applications, it is difficult to produce a yarn such as for carpet by these methods which can be piece dyed. It has been discovered that variabilities in the tensional stresses and other conditions imposed on the yarn during the crimping process produce variations in the yarn which are magnified in the subsequent dyeing of the yarn. Such variations show up in the end product, such as carpets, knits, Woven fabrics and the like, as streaks, worms or other imperfections due primarily to bulk and dye variations imparted to the yarn during crimping. Because of these variations, the art has often had to resort to the package dyeing or space dyeing of the yarn prior to producing the end product and then matching the yarn shades to obtain uniformity. It is more preferred in most instances to produce the end product such as a carpet, and then to piece dye the product, e.g., dye the carpet in its entirety. Under such conditions, any variation in the yarn shows up as streaks in the product, thus reducing the value thereof. Because of this, yarn suitable for piece dyeing commands a higher price and is actively sought by the industry.

The apparent recognition in the art for the need to control such variations has led to numerous means for controlling yarn removal from stuffer boxes. Such means have included springs, hinge doors, channels, programmed nip rollers and the like. However, such mechanically controlled means have been found to be less than fully satisfactory. Sudden fluctuations in yarn removal still result, particularly with continuous filaments, because of temporary and periodic yarn hangups in the stuifer box. As

a consequence, sudden increases and decreases in the tension of the yarn being removed from the stuffer box occur, thus imparting variations to the yarn which affects the quality of the resulting yarn.

It is therefore an object of the present invention to provide an apparatus and a method for reducing and, in many instances, eliminating yarn imperfections by reducing yarn tension variations to a minimum. It is another object of the present invention to provide a stuffer boxapparatus which eliminates all moving parts other than the feed means, thus aiding in reducing crimping variations. It is a further object of the present invention to provide a stutfer box crimper which reduces or entirely eliminates yarn hangups in the crimping chamber and permits the free release of crimped yarn from the stuffer box. These other objects will become apparent to those skilled in the art from the description which follows.

THE INVENTION In accordance with the invention, a stutter box crimper is provided for crimping fibers comprising an elongated chamber and feed means for said chamber, said chamber comprising a fiber compaction area and a fiber exit area, said compaction area comprising substantially parallel fiber guide means in the plane of said feed means and substantially parallel fiber confining means in a plane 45 to degrees displaced from the plane of the feed means, said exit area comprising diverging fiber confining friction-reducing means and corresponding converging fiber back-pressure producing means in a plane 45 to 135 degrees to said feed means, said diverging and converging means co-acting to translate fiber frictional force from the plane of the feed means to the plane of the back pressure means.

A method is provided for stuffer box crimping of fibers comprising continuously feeding a bundle of fibers to a restriction chamber, crimping, folding over and lapping said bundle of fibers as they are fed to said chamber to form primary folds of fibers which fold against two opposed Walls of said chamber, forcing said fibers through said chamber by the mass of continuously fed fibers thereby producing a forwarding pressure on said fibers through said chamber and a frictional force by said fibers against said opposing walls, diverging said opposing walls to reduce the fiber frictional force against said walls while imposing a back pressure on said fibers by converging a third Wall portion of said chamber against said fibers to increase the frictional force on said fibers in a direction 45 to 135 degrees from the direction of the primary folds in said fibers in said chamber, thereby permitting the free release of crimped fibers from said chamber.

The present invention provides a method for stuffer box crimping fibers or yarn in a manner whereby the yarn can be continuously withdrawn from the crimper under zero tension, if desired, without hangups or fluctuations in tensions on the yarn exiting from the crimper. In the preferred method of operation, the yarn is actually extuded from the stutter box, thus enabling the crimper to operate with a zero yarn draw-out tension. Of course, a small yarn exit tension can be used such as about 0 to 0.1 and more preferably 0 to 0.05 gram per denier, but it has been found to be particularly desirable to avoid such tensions. Previous stuffer box crimpers and methods of operation resulted in the folds in the yarn being caught against the sidewalls of the crimper, thereby temporarily trapping the yarn. Because such crimpers utilize Withdrawal means, the yarn tensions in the exit sections fluctuated rapidly and Without control due to the periodic temporary entrapment of the yarn in its own folds against the crimper walls. The present method and apparatus provides the means and method for eliminating yarn variations by re- 3 ducing or eliminating tension required to remove the yarn from the stutter box. Thus tension variations do not occur and are not introduced into the yarn in a manner which will subsequently affect the dyeability and other bulk yarn properties.

DETAILS OF THE INVENTION The invention will be best described by reference to the drawings wherein:

FIG. 1 is an elevation view, with a partial cut away of a stutfer box crimper made in accordance with the present invention;

FIG. 2 is a longitudinal sectional view along line 2--2 of FIG. 1;

FIG. 3 is an isometric view of another variation of the stuffer box crimper of the present invention;

FIG. 4 is a tension trace illustrating the uniformity of tension on yarn being withdrawn from the crimper of FIG. 1; and

FIG. 5 is a tension trace illustrating the prior art.

A stulfer box crimper of the present invention comprises feed means, a compaction area and an exit area. Feed means are rollers 12, sometimes referred to as nip rolls, which feed yarn 14 into the compaction area or stufier chamber 19. The yarn is crimped by the feed rollers and further folded, lapped and crimped as it is passed into the stuffer chamber. Feed rollers 12 continuously feed and compress yarn into primary crimping area 16 at the inlet of the stuffer chamber thereby forming the primary crimps. Stuffer chamber 19 is formed by two opposing sidewalls in the same plane as the nip rolls 12, called doctor blades 18, and a second pair of opposed walls called backplate 28 and frontplate 22. Backplate 28 and frontplate 22 form the guide means which retain the crimped fibers between doctor blades 18 against which the crimped yarn folds and packs. Fiber in the compaction area is folded over and lapped against the walls formed by the doctor blades and frictionally engages said blades. Thus, secondary crimps are imposed in the fibers due to the folding over and lapping of the yarn up against the blades. The continuous feeding of the yarn to the compaction area forces the yarn downwardly through the chamber. The doctor blades are preferably positioned to provide a primary divergence from each other in a small degree to control the frictional force exerted on the yarn as it is forced through the compaction area.

The divergence of the doctor blades is on the order of 0.001 to 0.1 inch per inch along the length of the compaction area and more preferably about 0.002 to 0.08 inch per inch. The particular divergence used depends on the particular yarn being crimped, the yarn finish, if any, the filament cross section, and the resulting co-efficicnt of friction obtained between the yarn and walls. The divergence is chosen to provide the needed compaction force to set the crimp in the chamber length while providing for smooth passage of the yarn plug therethrough. A particularly preferred divergence for nylon continuour filament carpet yarn is about 0.002 to 0.01 inch per inch.

While the compaction area can be heated to aid in crimp setting, the frictional engagement of the yarn against the opposed walls 18 normally creates sufficient heat on continuous operation to aid in the crimp setting thereby eliminating the requirement of additional heating although such can be used if desired.

The exit area of the stuffer box is formed by a secondary further divergence 26 of the doctor blades 18. A corresponding convergence of stabilizer 34 mounted in frontplate 22 and/or backplate 28 begins in the compaction area and forms the back pressure means. The secondary divergence is of a greater amount than the primary divergence and is preferably in an amount of about 0.001 to 0.5 inch per inch along the stuffer chamber and more preferably about 0.015 to 0.25 inch per inch. While a particularly preferred secondary divergence is illustrated,

4 the divergence can take another form such as a double angle.

In a preferred embodiment, stabilizer groove 30 is positioned in face plate 22 in the exit area for the mounting of stabilizer 34 which is positioned to converge onto and against the crimped yarn. In the same manner, a second stabilizer can be positioned in backplate 28 so as to also converge against the yarn in the crimping chamber if so desired. Stabilizer 34 is machined and mounted so as to form a primary convergent area 36 within the stuffer box which in the preferred embodiment subsequently tapers to a constant nonconverging area 38 which retains the applied convergence in the crimping chamber. The convergent area 36 of stabilizer 34 provides the back pressure on the yarn in the crimping chamber and is readily adjustable to control the point of yarn take-off 40, which in turn is a function of the back pressure, divergence and convergence areas. Mounting holes 32 are provided for the assembly and adjustment of the stuffer chamber.

As yarn 14 passes through the crimping chamber 19, the yarn folds against the doctor blades 18 and tend to restrict the movement of the yarn through the chamber, thereby producing a leading bulge 42 in the center of the chamber with the folds 44 tending to follow bulges 42 in the passage of the yarn plug through the crimping chamber. As the yarn reaches the convergence area formed by stabilizer 34, the back pressure created by stabilizer 34 causes the bulges to reverse and the folds 44 to catch up to the bulges 42 so as to be substantially even therewith. Thus the crimped yarn can be extruded from the crimper at yarn take-off point without slugging and catching, thus varying yarn take-off tensions which normally accompanies in-column yarn hangups due to the folds being compressed against the crimper sidewalls. In this manner, the yarn can be continuously extruded or withdrawn at a substantially constant low tension without periods of sudden tension variations. This is more clearly illustrated in FIG. 4 which shows a tension trace of yarn being withdrawn from the described crimper compared to the tension trace shown in FIG. 5 which illustrates the wide erratic tension variations which occur with prior art stuffer boxes and methods.

In a preferred embodiment of the present apparatus, backplate 28 and faceplate 22 are preferably recessed away from feed rollers 12, thereby providing sufficient space for the free downward movement of yarn fed into the chamber. In this manner, the back and faceplates serve primarily as guide means while the opposed walls, e.g., doctor blades, serve to form the primary confining and compaction area. Also, while stabilizer 34 is preferably rigidly mounted in association with the stuffer chamber, such stabilizer could be mounted for limited flexibility. Of particular importance is the fact that stabilizer 34 is mounted in a plane parallel to the doctor blades 18 and displaced 45 to 135 degrees from the plane of the doctor blades and feed rollers. In the most preferred embodiment, the stabilizer is mounted in a parallel plane 90 degrees, e.g., at right angles to the doctor blades.

FIG. 3 illustrates a further embodiment of the present invention wherein the opposed walls forming the compaction area and the guide means are machined together in a two component unit thereby providing a combination doctor blade and guide means 46 wherein lip 48 forms the guide means and groove 50 comprises the doctor blade. Proceeding along the chamber from the inlet and at feed rollers 12 toward exit end 52 of the crimper, groove 50 diverges outwardly while lip 48 converges inwardly thereby providing a chamber having the functional characteristics of that described in FIGS. 1 and 2. While such chambers have advantages in simplicity and ready duplication of numerous stufier boxes with the same tolerances, the ability to adjust an operating crimper is somewhat limited.

The yarn produced by the present crimper is of a generally saw-tooth configuration with primary and secondary crimp amplitudes. The number of crimps per inch can be varied by adjustments in the operation conditions so as to yield about to 30 crimps per inch and more preferably about 8 to crimps per inch. In a similar manner, the skein length of crimped yarn can be varied from about 12 inches to about 19 inches as may be desired.

While the invention has been described more particularly with reference to the crimping of yarns, the present apparatus is particularly suitable for crimping continuous filament synthetic yarns such as carpet yarns, weaving yarns, knitting yarn and the like, such as nylon, polyester, cellulose acetate and triacetate, acrylics, spandex and like synthetic filaments. The simplicity and smooth functioning of the present apparatus is of particular advantage When used with continuous filaments because of the elimination of tendencies to hang up filaments throughout the apparatus. This is particularly true when crimping relatively strong filaments such as nylon and polyester, which do not readily break under the applied tensions. While the apparatus is particularly suitable for crimping continuous filaments, it will be appreciated that staple yarns can also be crimped in a corresponding manner.

While the apparatus described is particularly suitable for stutfer box crimping yarns having a total denier from' about 100 to 5000, and denier per filament of about 1 to 50 and more preferably about 3 to 20, yarns of greater or lesser total denier can also be suitably crimped by adjusting the size of the component parts such as the particular compaction chamber area, the desired length of the compaction column, the amount of divergence and convergence and the like, as described herein. Such adjustments are readily made by those skilled in the art.

While there have been described various embodiments of the present invention, the methods and apparatus described herein are not intended to be understood as limiting the scope of the invention, as it is realized that changes therein are possible. It is intended to cover the invention broadly being limited only by the appended claims.

What is claimed is:

1. A stufier box crimper for crimping fibers comprising an elongated chamber and feed means for said chamber, said chamber comprising a fiber compaction area and a fiber exit area, said compaction area comprising substantially parallel fiber guide means in the plane of said feed means and substantially parallel fiber confining means in a plane 45 to 135 degrees displaced from the plane of the feed means, said exit area comprising diverging fiber confining friction-reducing means and corresponding stationary, but adjustable, converging fiber back-pressure producing means in a plane 45 to 135 degrees to said feed means, said diverging and converging means co-acting to translate fiber frictional force from the plane of the feed means to the plane of the back pressure means.

2. The apparatus of claim 1 wherein the confining means comprises a pair of opposing doctor blades.

3. The apparatus of claim 2 wherein the doctor blades are positioned to form a primary divergence in the compaction area and a secondary greater divergence in the exit area.

4. The apparatus of claim 1 wherein the guide means comprises a front and back plate.

5. The apparatus of claim 4 wherein a stabilizer is positioned in at least one of said front or back plate to converge into said exit area and impede the movement of fiber therethrough.

6. The apparatus of claim 1 wherein the cross-sectional area of the elongated chamber remains about constant in the compaction area and the exit area while the inside fiber contacting peripheral geometry changes.

7. The apparatus of claim 1 wherein the back pressure producing means is a stabilizer mounted in a plane at a right angle to said confining means in said exit area.

8. The apparatus of claim 1 wherein the feed means are a pair of nip rolls.

9. A method for stutter box crimping of fibers comprising continuously feeding a bundle of fibers to a restriction chamber, crimping, folding over and lapping said bundle of fibers as they are fed to said chamber to form primary folds of fibers which fold against two opposed walls of said chamber, forcing said fibers through said chamber by the mass of continuously fed fibers thereby producing a forwarding pressure on said fibers through said chamber and a frictional force by said fibers against said opposing walls, diverging said opposing walls to re duce the fiber frictional force against said walls while imposing a back pressure on said fibers by converging a third stationary, but adjustable wall portion of said chamber against said fibers to increase the frictional force on said fibers in a direction 45 to degrees from the direction of the primary folds in said fibers in said chamber, thereby permitting the free release or crimped fibers from said chamber.

10. The method of claim 9 wherein the bundle of fibers are continuous filaments.

11. The method of claim 10, wherein the bundle of continuous filaments is a carpet yarn.

12. The method of claim 9 wherein the crimped fibers are extruded from said chamber.

References Cited UNITED STATES PATENTS LOUIS K. RIMRODT, Primary Examiner US. Cl. X.R. 

